The present disclosure relates to a distance measuring device and more particularly relates to a distance measuring device which measures a distance by the delay of light using a light source and a solid-state image sensor.
In recent years, three-dimension (3D) distance measuring devices (rangefinders) for measuring distances and determining shapes have caught a lot of attention, thanks to the appearance of KINECT by Microsoft. Moreover, in order to meet the demands for lowering the prices of such 3D devices, a single sensor is increasingly required to handle the distance measurements under various conditions, e.g., no matter whether the object is located at a short distance or a long distance and whether the object forms part of a bright area or a dark area. To meet such a request, a method currently under study involves multiple exposures to measure the distance. However, the method uses a frame memory to measure the distance under different conditions, and, as a result, the cost tends to increase as a distance measurement set as a whole.
In Japanese Unexamined Patent Publication No. 2012-195734 (FIG. 19), for example, an image signal processor includes a frame memory. The frame memory stores digital image data to which a correction such as shading has been made. In response to a request from the image signal processor, the digital image data in the frame memory is output via an interface. Using a time-of-flight (TOF) measuring technique, for example, the image signal processor measures the TOF of light by receiving the light that has irradiated, and has then been reflected from, the object. Based on the measured TOF of the light, the image signal processor measures the distance to the object and obtains a 3D image of the object.